From 0de4cb473aed57ee4ba7e0551ad27bddc19fc519 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Tue, 28 Apr 2026 08:10:43 -0700 Subject: workqueue: fix devm_alloc_workqueue() va_list misuse devm_alloc_workqueue() built a va_list and passed it as a single positional argument to the variadic alloc_workqueue() macro: va_start(args, max_active); wq = alloc_workqueue(fmt, flags, max_active, args); va_end(args); C does not allow forwarding a va_list through a ... parameter. alloc_workqueue() expands to alloc_workqueue_noprof(), which runs its own va_start() over its ... params, so the inner vsnprintf(wq->name, sizeof(wq->name), fmt, args) in __alloc_workqueue() received the outer va_list object as the first variadic slot rather than the caller's actual format arguments. Add a new static helper alloc_workqueue_va() that wraps __alloc_workqueue() and runs wq_init_lockdep() on success, and fold both alloc_workqueue_noprof() and devm_alloc_workqueue_noprof() onto it as suggested by Tejun. The wq_init_lockdep() step is required on the devm path too, otherwise __flush_workqueue()'s on-stack COMPLETION_INITIALIZER_ONSTACK_MAP would NULL-deref wq->lockdep_map. No caller changes are required. devm_alloc_ordered_workqueue() is a macro forwarding to devm_alloc_workqueue() and inherits the fix. Two in-tree callers actively trigger the broken path on every probe: drivers/power/supply/mt6370-charger.c:889 drivers/power/supply/max77705_charger.c:649 both of which use devm_alloc_ordered_workqueue(dev, "%s", 0, dev_name(dev)). A standalone reproducer module is available at[1]. Link: https://github.com/leitao/debug/blob/main/workqueue/valist/wq_va_test.c [1] Fixes: 1dfc9d60a69e ("workqueue: devres: Add device-managed allocate workqueue") Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- include/linux/workqueue.h | 6 ++++-- kernel/workqueue.c | 28 +++++++++++++++++++--------- 2 files changed, 23 insertions(+), 11 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index ab6cb70ca1a5..6177624539b3 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -534,8 +534,10 @@ alloc_workqueue_noprof(const char *fmt, unsigned int flags, int max_active, ...) * Pointer to the allocated workqueue on success, %NULL on failure. */ __printf(2, 5) struct workqueue_struct * -devm_alloc_workqueue(struct device *dev, const char *fmt, unsigned int flags, - int max_active, ...); +devm_alloc_workqueue_noprof(struct device *dev, const char *fmt, + unsigned int flags, int max_active, ...); +#define devm_alloc_workqueue(...) \ + alloc_hooks(devm_alloc_workqueue_noprof(__VA_ARGS__)) #ifdef CONFIG_LOCKDEP /** diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5f747f241a5f..24d0265191d4 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5906,6 +5906,20 @@ err_destroy: return NULL; } +static struct workqueue_struct *alloc_workqueue_va(const char *fmt, + unsigned int flags, + int max_active, + va_list args) +{ + struct workqueue_struct *wq; + + wq = __alloc_workqueue(fmt, flags, max_active, args); + if (wq) + wq_init_lockdep(wq); + + return wq; +} + __printf(1, 4) struct workqueue_struct *alloc_workqueue_noprof(const char *fmt, unsigned int flags, @@ -5915,12 +5929,8 @@ struct workqueue_struct *alloc_workqueue_noprof(const char *fmt, va_list args; va_start(args, max_active); - wq = __alloc_workqueue(fmt, flags, max_active, args); + wq = alloc_workqueue_va(fmt, flags, max_active, args); va_end(args); - if (!wq) - return NULL; - - wq_init_lockdep(wq); return wq; } @@ -5932,15 +5942,15 @@ static void devm_workqueue_release(void *res) } __printf(2, 5) struct workqueue_struct * -devm_alloc_workqueue(struct device *dev, const char *fmt, unsigned int flags, - int max_active, ...) +devm_alloc_workqueue_noprof(struct device *dev, const char *fmt, + unsigned int flags, int max_active, ...) { struct workqueue_struct *wq; va_list args; int ret; va_start(args, max_active); - wq = alloc_workqueue(fmt, flags, max_active, args); + wq = alloc_workqueue_va(fmt, flags, max_active, args); va_end(args); if (!wq) return NULL; @@ -5951,7 +5961,7 @@ devm_alloc_workqueue(struct device *dev, const char *fmt, unsigned int flags, return wq; } -EXPORT_SYMBOL_GPL(devm_alloc_workqueue); +EXPORT_SYMBOL_GPL(devm_alloc_workqueue_noprof); #ifdef CONFIG_LOCKDEP __printf(1, 5) -- cgit v1.2.3 From 20e81c64c905bd765e69ef07920d2b1130dc79b6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 29 Apr 2026 09:44:16 -1000 Subject: workqueue: Annotate alloc_workqueue_va() with __printf(1, 0) alloc_workqueue_va() forwards its va_list to __alloc_workqueue() which ultimately feeds vsnprintf(). __alloc_workqueue() already carries __printf(1, 0); the new wrapper needs the same annotation so format string checking propagates through the forwarding. Fixes: 0de4cb473aed ("workqueue: fix devm_alloc_workqueue() va_list misuse") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202604300347.2LgXyteh-lkp@intel.com/ Signed-off-by: Tejun Heo --- kernel/workqueue.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 24d0265191d4..3d2e3b2ec528 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5906,6 +5906,7 @@ err_destroy: return NULL; } +__printf(1, 0) static struct workqueue_struct *alloc_workqueue_va(const char *fmt, unsigned int flags, int max_active, -- cgit v1.2.3